The Semantic Web is an evolving collection of software tools and content, which provides information on the Internet, or World Wide Web, in such a way that it can be readily used by intelligent agents and other computer programs. Information on the Semantic Web, rather than being in natural language text, can be maintained in a structure workable by both computers and people. The Resource Description Framework (RDF) from the World Wide Web Consortium (W3C) underlies most Semantic Web efforts. RDF consists of statements (subject-predicate-object triples) made about instances of specific classes (similar to an object-oriented programming language).
The Resource Description Framework (RDF) is a general framework for how to describe an Internet resource such as a Web site and its content. An Internet resource is defined herein as a resource with a Uniform Resource Identifier (URI), including the Uniform Resource Locators (URLs) that identify Web sites as well as specific Web pages. Resources can also be physical objects (such as people) represented on Web pages. As with known HyperText Markup Language (HTML) META tags, the RDF description statements, encased as part of an Extensible Markup Language (XML) section, can be included within a Web page (HTML file), or can be in separate files.
RDF description statements can be represented as graphs containing nodes (instances or string literals) and arcs (statements). FIG. 6A provides an example of such a graph for an RDF statement of the form, “Mike Thornton has a father Joe Thornton.” For this RDF statement, “Mike Thornton” is the subject, “father” is the predicate, and “Joe Thornton” is the object. In the exemplary diagram, or graph of FIG. 6A, the ovals can illustrate nodes representing resources (ovals 2 and 4), and arcs can represent the named property, as shown by arc 6. The direction of the arc can be from subject (2) to object (4). It can be understood that other representations besides the illustrated ovals and directional arcs can be used.
FIG. 6B illustrates a graph of a collection of statements in which “Mike Thornton” (using an abbreviated form to represent a full URI) can be both the subject and object of various ones of the statements, including, “Jason Thornton has a father Mike Thornton,” and “Mike Thornton is married to Nancy Frier.” The subject “Jason Thornton” is represented by oval 8 and predicate “father” is represented by arc 10 from subject “Jason Thornton” (oval 8) to object “Mike Thornton” (oval 2). The object “Nancy Frier” is represented by oval 12 and predicate “married to” is represented by arc 14 from subject “Mike. Thornton” (oval 2) to object “Nancy Frier” (oval 12).
While such graphs as illustrated in FIGS. 6A and 6B can pictorially present the properties of subjects and objects, they can do so in a static fashion. For example, FIG. 6C can illustrate an extended graph for statements concerning “Mike Thornton” taken from a genealogical resource. In addition to the statements in FIG. 6R, FIG. 6C can include the statements shown in Table 1.
StatementSubject (Identifier)Predicate (Identifier)Object (Identifier)Mike Thornton has aMike Thornton (2)mother (16)Louise Hensley (18)mother Louise HensleyNoah Thornton has aNoah Thornton (22)father (24)Mike Thornton (2)father Mike ThorntonJason Thornton has aJason Thornton (8)mother (20)Nancy Frier (12)mother Nancy FrierNoah Thornton has aNoah Thornton (22)mother (26)Nancy Frier (12)mother Nancy FrierJoe Thornton is marriedJoe Thornton (4)married to (28)Louise Hensley (18)to Louise Hensley
It can be seen that Mike Thornton is neither the subject nor object of the last three statements in Table 1. However, these statements can be included in the graphical representation as having both subjects and objects in common with statements concerning “Mike Thornton.”
Without additional statements providing dates for such events as births, deaths, or marriages, a user cannot determine time varying information from the graphs of FIGS. 6A-C. For example, one cannot assess whether Noah is older or younger than Jason, or the relative ages of other individuals shown. Other time varying information, such as multiple marriages, can also present difficulties for the representations of FIGS. 6A-C. Methods and systems are needed for determining and graphically representing such information from Semantic Web structured resources to a user.